package api;

import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONUtil;
import lombok.SneakyThrows;
import model.Article;
import util.DBUtils;
import util.ResultUtils;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

/**
 * @Author: wenjingyuan
 * @Date: 2023/04/02/20:40
 * @Description:
 */
@WebServlet("/artlist")
public class ArtListServlet extends HttpServlet {
    @SneakyThrows
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        List<Article> data=new ArrayList<>();
        String msg="未知错误！";
        //1.从前端获取参数并进行效验
        String currPage=req.getParameter("cp");
        String pageSize=req.getParameter("ps");
        int cp=1;
        int ps=2;
        if(!StrUtil.isBlank(currPage)){
            cp=Integer.valueOf(currPage);
        }
        if(!StrUtil.isBlank(pageSize)){
            ps=Integer.valueOf(pageSize);
        }
        //2.使用分页查询从数据库拿到数据
        Connection connection= DBUtils.getConnection();
        String sql="select * from article order by aid desc limit ? offset ?";
        PreparedStatement statement=connection.prepareStatement(sql);
        statement.setInt(1,ps);
        statement.setInt(2,(cp-1)*ps);
        ResultSet resultSet= statement.executeQuery();
        while(resultSet.next()){
            Article article=new Article();
            article.setAid(resultSet.getInt("aid"));
            article.setTitle(resultSet.getString("title"));
            String ctime = resultSet.getString("createtime");
            article.setCreatetime(ctime.substring(0,ctime.lastIndexOf(".")));
            String context=resultSet.getString("context");
            context = context.replace("#", "");
            int maxSize=Integer.min(50,context.length());
            article.setDesc(context.substring(0,maxSize));
            data.add(article);
        }
        msg="成功";
        DBUtils.close(resultSet,statement,connection);
        //3.将数据返回给前端
        resp.setContentType("application/json;charset=utf-8");
        resp.getWriter().println(JSONUtil.toJsonStr(ResultUtils.toResult(200,data,msg)));
    }
}
